Senate Majority Leader Mitch McConnell (R-Ky.) and his leadership team are seriously considering voting on a bill that would scale back the federal government’s role in the health care system and instead provide block grants to states, congressional and Trump administration sources said.

It would be a last-ditch attempt to repeal Obamacare before the GOP’s power to pass health care legislation through a party-line vote in the Senate expires on Sept. 30.

No final decision has been made, but the GOP leader has told his caucus that if the bill written by Sens. Lindsey Graham (R-S.C.) and Bill Cassidy (R-La.) has the support of at least 50 of the 52 GOP senators, he will bring it to the floor, Graham and Cassidy say. That would give Republicans one more crack at repealing the Affordable Care Act, a longtime party pledge.

Right now, support for the bill — which would replace Obamacare’s tax subsidies with block grants, end the law’s individual insurance mandate and scale back its Medicaid expansion — among Republican senators is short of 50 votes. But McConnell and his lieutenants will gauge support this week in private party meetings with help from President Donald Trump, administration and Capitol Hill sources said.

“McConnell and his team are engaged and serious about the vote and working with the conference to build support for Graham-Cassidy,” a source familiar with the bill’s prospects said Sunday. The “White House is also operating with all hands on deck.”

White House officials began making calls last week to Republican Senate officesand plan to whip Senate votes this week, an administration official said. Supporters of the Graham-Cassidy bill have tried to keep their efforts to round up votes quiet so far, this official said, but the push is ramping up.

Graham has publicly begged for Trump to help build support for the bill, and it appears to be paying off. The president asked about the Graham-Cassidy proposal in conversations this weekend in Bedminster, New Jersey, and is likely to call senators this week while he is in New York at the United Nations, the administration official said, though much of the work will be done on the senior staff level.

The new activity marks a significant shift for GOP leaders after several senior Republican senators panned the bill’s prospects earlier this month. But Cassidy estimates he is now just a handful of votes short of passing the bill, and other senators are beginning to press for another vote before they turn their attention to tax reform this fall.

Some Republicans believe that if the bill were put on the floor Monday, it would have the support of 49 senators.

“All we need is one more,” Sen. Pat Roberts (R-Kan.) said of the repeal effort, which failed in July after GOP Sens. John McCain of Arizona, Susan Collins of Maine and Lisa Murkowski of Alaska voted no on a slimmed-down repeal bill.

Graham and Cassidy’s bill amounts to a new approach and was introduced just last week, but Senate Republicans have already sent it to the Congressional Budget Office for analysis and have demanded the agency expedite the score, a Republican aide said. The Senate is in sessiononly three days this week, so any Obamacare repeal vote would occur the last week of September, giving the CBO another week or so to evaluate the proposal. A bipartisan fiscal funding deal passed earlier than usual this month, leaving the Senate GOP with an opening at the end of a month usually filled with brinkmanship.

McConnell is expected to discuss the matter with his leadership team on Monday, then weigh support for the bill with his full caucus on Tuesday. At lunch last Thursday, most of the caucus pushed for another try on health care, and McConnell was favorably inclined, as long as it won’t fail again.

“McConnell is behind it,” Graham said in an interview late last week. Republicans are “not going to tolerate us just sitting around saying we did the best we could. One and done is not going to do it.”

It’s an incredibly steep task. Sen. Rand Paul (R-Ky.) said he is a “no,” panning the bill as “Obamacare lite.” And Republicans believe Collins also won’t vote for it, though she has not made a final decision. Graham-Cassidy backers can’t afford to lose another vote.McCain has been cautiously open to the approach, but some more conservative senators could scuttle it since the bill keeps many of Obamacare’s taxes. Some senators are expected to wait until the CBO score arrives until making a final decision.

The White House is aware the votes aren’t yet there, the administration official said: “It’s still a long ways to go.”

Republicans say McConnell won’t bring up the bill if there is any chance of failure, given the dramatic collapse in the summer.

“McConnell would like something to pass. But he also knows that getting 50 to vote for that is a challenge,” said a Republican aide tracking the bill. “They show him it has 50, he’ll schedule a vote.”

Even if the bill passes the Senate, there is no guarantee the House would take it up — and if it did, Speaker Paul Ryan and his caucus would have to pass the bill with no changes due to the Senate’s deadline to use “reconciliation.” The House passed a dramatically different Obamacare bill this spring.

Despite the long odds, Senate Republicans are hesitant to give up given the beating they have taken from the president, his staff and the GOP base. If the Senate GOP could revive Obamacare repeal, it would help lift a cloud of conservative angst hanging over the Senate majority after July’s failure.

The collapse of that effort is hurting incumbent senators up for reelection and could fuel primary challenges next year, senators said.

And passage of a repeal bill could get the Senate GOP back in the good graces of Trump, who has repeatedly courted Democratic leaders Nancy Pelosi and Chuck Schumer this month. Trump is obsessed with action on repeal of Obamacare, a seven-year GOP campaign promise, and his urgency will only heat up as a deadline looms, officials said.

“He keeps saying ‘repeal and replace, repeal and replace,’” said a second administration official. “He is going to keep pushing for something on this.”